Lamp assembly



June 1967 LA VERN L. LINSE ETAL 3,328,574

LAMP ASSEMBLY Filed Dec. 8, 1964 INVENTORS Z4 l EP/V L. I. INSE flex/A20 a Ha /9J2. X

United States Patent Ramsey County,

This invention relates to lamp-holders, more particularly to spring-loaded mountings for high intensity incandescent filament electric lamps as used in exposure and projection apparatus.

One very effective light source for overhead projectors and the like is the iodine vapor tungsten filament lamp having a coiled filament mounted in a tubular transparent quartz envelope containing small amounts of iodine and with external contact points at opposite ends of the tube. A typical commercially available embodiment is the GE FAL lamp. These lamps have very high operating temperatures and accordingly are necessarily supported in socket members of heat-resistant ceramic materials.

The present invention provides novel mountings for tubular lamps of the type described. The lamp is easily installed, and as easily removed, without requiring any direct manipulation of the socket. The lamp is necessarily enclosed within its protective shield during use.

These and other advantages are obtained by employing a spring-mounted socket member in conjunction with a light shield having a cooperating spring member capable of overcoming the socket-supporting spring and eflecting contact between socket and lamp when tthe shield is pressed into closed position.

In the drawing, FIGURE 1 is an elevation, mainly in section, showing the lamp as inserted within the mounting and with the light shield in closed position; and FIGURE 2 illustrates in perspective the socket components, with the light shield member in open position.

A base plate having a central opening 11 supports a fixed socket member 12, a spring-mounted socket member 13, and an open top light shield 14.

The ceramic socket member 12 is rigidly attached to a ledge 15 forming a part of the base 10 by means of rivets 21. A contact member 16 protrudes from the same side of the socket at the center of a semicircular boss 17 and is connected to a cable 19 passing through the member 12 and held in place at the outer surface by an insulating strip 20 which in turn is aflixed to the ceramic socket by rivets 21. The cable is further sealed in place within a channel 18 in the ceramic socket, by means of temperature-resistant insulating sealing compound.

A forwardly olfset brace member 22 serves to support the constricted end of the lamp 23 in position for being pressed into contact with the contact member 16.

The opposite socket member 13is generally of similar structure but is mounted on a curved leaf spring 24 secured to the base 10 through rivets 25 and to the porcelain socket member by rivets 26. The socket includes a contact 27 centered within a semicircular boss 28 and making contact with cable 31 which is sealed within a channel 29 and held in place with an insulating bar 30 also held in place by rivets 26.

A shield assembly 14 is hingedly supported on the base 10 at pivots 32. The shield may be locked in closed position by spring catch 33 fitting in matching orifice 34. In that position the leaf spring 35, supported on an outcontact member 27 into firm contact 2 wardly oflset edge portion 36 of the shield 14, presses against the socket 13 with suificient force to overcome the resistance of the supporting spring 24 and force the with the lamp 23. At the same time the other end of the lamp is forced against the contact member 16 of the socket 1-2.

In an exemplary structure the spring 24 consists of an approximately /8 x 1% inch segment of ten mil stainless steel. The spring 35 consists of a T-shaped strip of 16 mil stainless steel, the stem of the T being slightly more than one-half inch in width, the tips of the cross-piece being riveted to the oifset portion 36 of the cover 14. The force required at the outer upper edge of the socket 13 to achieve adequate contact pressure at both ends of the lamp is approximately three pounds, and is about one-half the force required to press the upper portion of the spring 35 a distance equal to the motion required to provide such contact.

A semispherical reflector 37 held in place in the opening 11 by brace 22 and clamps 38 serves to direct the light from the lamp 23 upwardly through the surrounding shield 14 when the assembly is held in the upright position indicated in FIGURE 1 and as typically employed in an overhead projector. Cooling air then circulates through the several openings in the base 10 and the lower portions of the shield 14, upwardly past the lamp and through the shield. The entire assembly is preferably resiliently and adjustably mounted above a supporting floor in the projector body, e.g. by spring and bolt support means located at apertures 39 in the base 10, for vertical adjustment and focusing of the light source.

During operation the assembly becomes heated to temperatures suflicient to cause severe burning it touched. Failure of the lamp at such times would normally require a waiting period for cooling of the lamp, sockets, and shield before a new lamp could be substituted. With the present lamp assembly all that is required is to swing back the shield 14, by lifting with a pencil inserted in the hole 40 provided for the purpose, thereby at the same time permitting the socket 13 to spring away from the lamp. The lamp may then be flipped out with the pencil, a new lamp dropped in place, and the shield returned to the closed position so that image projection may continue with a delay of no more than a few seconds.

What is claimed is as follows:

1. A lamp assembly adapted for use in an overhead projector, comprising a base centrally supporting a concave semispherical reflector, a first socket member rigidly supported from said base at one side of said reflector, a second socket member spring-mounted to said base at the opposite side of said reflector and biased away from said first socket member to provide between said members a space sufiicient to permit a tubular lamp member to be loosely supported by said socket members above and in line with said reflector, and a surrounding shield, open in line with said reflector, hingedly attached to said base and carrying a flat spring member aligned with said second socket member and of suflicient strength to force said second socket member toward said first socket member and against the biasing of the spring-mounted member for providing secure electrical contact with said lamp at each of said socket members when said shield is in closed position.

2. In a lamp assembly for an overhead projector wherein a pair of socket members for supporting a high intensity tu'bular lamp are disposed on a supporting base ,3 4 at opposite sides of a condensing reflector and within an interposed lamp when said shield is rotated into closed open-ended shield hingedly attached to said base, the imposition. provement comprising: a resilient curved leaf spring R f r Cited mounting for supporting one of said socket members on said base in a position normally biased away, from the 5 UNITED STATES PATENTS other of said socket members, and a stronger opposing 2, 7 1945 Holecek 24051.11

leaf spring supported on said shield in position to force said one of said socket members toward said other of said NORTON Prlmary Exammersocket members against the bias of said curved spring to R. M, SHEER, A im Ex i obtain firm'contact between said socket rne'mbers'and an 10 

1. A LAMP ASSEMBLY ADAPTED FOR USE IN AN OVERHEAD PROJECTOR, COMPRISING A BASE CENTRALLY SUPPORTING A CONCAVE SEMISPHERICAL REFLECTOR, A FIRST SOCKET MEMBER RIGIDLY SUPPORTED FROM SAID BASE AT ONE SIDE OF SAID REFLECTOR, A SECOND SOCKET MEMBER SPRING-MOUNTED TO SAID BASE AT THE OPPOSITE SIDE OF SAID REFLECTOR AND BIASED AWAY FROM SAID FIRST SOCKET MEMBER TO PROVIDE BETWEEN SAID MEMBERS A SPACE SUFFICIENT TO PERMIT A TUBULAR LAMP MEMBER TO BE LOOSELY SUPPORTED BY SAID SOCKET MEMBERS ABOVE AND IN LINE WITH SAID REFLECTOR, AND A SURROUNDING SHIELD, OPEN IN LINE WITH SAID REFLECTOR, HINGEDLY ATTACHED TO SAID BASE AND CARRYING A FLAT SPRING MEMBER ALIGNED WITH SAID SECOND SOCKET MEMBER AND OF SUFFICIENT STRENGTH TO FORCE SAID SECOND SOCKET MEMBER TOWARD SAID FIRST SOCKET MEMBER AND AGAINST THE BIASING OF THE SPRING-MOUNTED MEMBER FOR PROVIDING SECURE ELECTRICAL CONTACT WITH SAID LAMP AT EACH OF SAID SOCKET MEMBERS SAID SHIELD IS IN CLOSED POSITION. 